DOCSLIB.ORG

Mechanics and Dynamics of Pinning Points on the Shirase Coast, West Antarctica

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mechanics and Dynamics of Pinning Points on the Shirase Coast, West Antarctica https://doi.org/10.5194/tc-2020-298 Preprint. Discussion started: 28 October 2020 c Author(s) 2020. CC BY 4.0 License. Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica Holly Still1 and Christina Hulbe1 1National School of Surveying, University of Otago, Dunedin, New Zealand Correspondence: Holly Still ([email protected]) Abstract. Ice rises and rumples, sites of localised ice shelf grounding, contribute to shelf-wide mechanics by generating lateral and basal shear stresses, upstream compression and downstream tension. Here, using a case study approach, we simulate Ross Ice Shelf (RIS) and tributary ice stream flow, with and without the Shirase Coast Ice Rumples (SCIR), to quantify the specific contribution of these features to flow dynamics. While longitudinal stretching, and thus ice velocity, increases in response 5 to pinning point removal, flow resistance generated by other grounded features also increases, providing a control on the magnitude of the velocity difference. Spatial variation in two parameters inferred during model initialisation, basal friction and ice softness, further condition the system response to the SCIR. MacAyeal Ice Stream (MacIS), located directly upstream of the SCIR, is less responsive to the loss of the ice rumples than the obliquely oriented Bindschadler Ice Stream due to zones of locally higher basal drag acting on the main trunk of MacIS. In the model, the larger basal drag acting on MacIS is itself, 10 via regional changes in driving stress, a consequence of the coupled ice shelf and ice stream response to the SCIR. We also find that inversion of present-day flow and thickness for basal friction and ice softness, without feature-specific tuning, leads to the incorrect representation of ice rumple morphology, and by extension, any parameter that is affected by the initialisation procedure. Where pinning point effects are important, model tuning that respects pinning point morphology is necessary to represent the ice sheet–ice shelf system as a whole. Viewed from the perspective of change detection, we find that changes to 15 the ice shelf geometry following removal of the SCIR are transient, as mass flux reduces thickness gradients in some areas and increases them in others, while changes to the ice streams persist, even without sustained grounding line retreat. 1 Introduction Ice shelves regulate the Antarctic contribution to sea level rise via their influence on grounding line position and tributary glacier dynamics. Individual ice shelves are regulated by environmental conditions including their geographic setting. An ice 20 shelf laterally confined within an embayment experiences reduced longitudinal tensile stress (and stretching) relative to an unconfined ice shelf due to lateral shearing where the ice flows past coastal features and islands (Sanderson, 1979; Haseloff and Sergienko, 2018). Where floating ice runs aground, a pinning point forms and resulting compression and shearing further reduce longitudinal stresses (Favier et al., 2012; Borstad et al., 2013; Favier and Pattyn, 2015; Berger et al., 2016). Altogether, the rate of mass flux is moderated in an effect commonly referred to as ‘flow buttressing’, a normal force exerted on upstream 25 grounded ice by the ice shelf (Dupont and Alley, 2005, 2006; Gudmundsson, 2013; Fürst et al., 2016). 1 https://doi.org/10.5194/tc-2020-298 Preprint. Discussion started: 28 October 2020 c Author(s) 2020. CC BY 4.0 License. The importance of pinning points to ice shelf stability and grounding line position has been widely examined observationally (e.g., Matsuoka et al., 2015). For example, the speed-up and grounding line retreat of Pine Island Glacier following loss of a pinning point has been documented by Bindschadler (2002), Rignot (2002), Jenkins et al. (2010) and Arndt et al. (2018), and the individual force balance contributions of various Antarctic pinning points have been computed from observational data by 30 Thomas (1973), Thomas (1979), Thomas and MacAyeal (1982), MacAyeal et al. (1987) and Still et al. (2019). More theoretical approaches examine coupled mass and momentum effects of pinning points across the interconnected ice shelf and ice sheet system. For example, Goldberg et al. (2009) conducted idealised simulations of grounding line position and mechanics with (and without) an ice rise to demonstrate how an ice rise can modify vulnerability to the marine ice sheet instability. Favier et al. (2012) demonstrated that local changes to ice thickness due to the emergence of a pinning point generate feedbacks 35 in the stress balance that can maintain the local thickness perturbation and thus the grounded feature. Fried et al. (2014) examined the emergence of ice rises in the Ross Ice Shelf (RIS) as a source of thickness transients that drove past grounding line transgression. Nias et al. (2016) simulated the Thwaites Glacier response to changing contact with a pinning point beneath its floating ice tongue and concluded that basal traction on the grounded ice was more important to the glacier response than the direct mechanical effects of the pinning point itself. All of these examples demonstrate the importance of non-local effects 40 of pinning points in the ice shelf and ice sheet system. By generating resistive stresses, pinning points modify the velocity pattern and, via advection, the thickness pattern of an ice shelf. The momentum and mass perturbations together must be balanced by changes in thickness and resistive stresses elsewhere in the ice shelf–ice sheet system. Enhanced deformation around a pinning point also affects ice properties such as ice crystal fabric and temperature, modifying softness and thus ice flow (e.g., Borstad et al., 2013). The aim of the present work 45 is to examine the complete system of mass and momentum adjustments using a case study approach for a collection of pinning points in the RIS, West Antarctica. The flow of the RIS is regulated by a diverse collection of ice rises and rumples, the surface morphological expressions of ice shelf flow over or around pinning points (Fig. 1). Ice rises have a distinct dome-shaped morphology with ice shelf flow diverging around the rise, while undulating ice rumples form where the ice continues to flow directly over the area of localised 50 grounding (Martin and Sanderson, 1980; Matsuoka et al., 2015). Large ice rises in the RIS include Crary Ice Rise, Roosevelt Island and Steershead Ice Rise. Smaller, unnamed ice rumples are located along the Siple and Shirase Coasts. A group of these ice rumples in the eastern RIS, which we refer to collectively as the Shirase Coast Ice Rumples (SCIR) were chosen for this study. While individual rumples in the SCIR complex are relatively small, the lightly–grounded and low basal traction features collectively generate flow resistance comparable to larger ice rises in the RIS (Crary Ice Rise, Steershead Ice Rise 55 and Roosevelt Island) (Still et al., 2019). The SCIR are located 60 km downstream from the grounding lines of the MacAyeal and Bindschadler Ice Streams (MacIS and BIS), two large outlet streams of the West Antarctic Ice Sheet, and within a cove upstream of Roosevelt Island. This setting stands out as a region of significant buttressing in the RIS (Reese et al., 2018) and the arrangement allows the mass and momentum balances to be examined in a non-simple geometry. Observational-data driven analysis provides a limited, snapshot-like view of recent conditions. Observed velocity and thick- 60 ness may be used directly to quantify effective flow resistance, for example, using a force budget approach (MacAyeal et al., 2 https://doi.org/10.5194/tc-2020-298 Preprint. Discussion started: 28 October 2020 c Author(s) 2020. CC BY 4.0 License. Figure 1. Pinning points in the RIS and the model domain boundary. Large pinning points are labelled: SCIR = the Shirase Coast Ice Rumples, RI = Roosevelt Island, SIR = Steershead Ice Rise and CIR = Crary Ice Rise. The colour map of surface ice velocity magnitude is from the MEaSURES velocity dataset (Rignot et al., 2011a). The black line indicates the grounding zone (Bindschadler et al., 2011). In each figure from hereon, datasets are mapped with a Polar Stereographic Projection with a central meridian of 0◦ and a standard latitude of 71◦S, and in most cases, overlayed onto the MODIS MOA (Haran et al., 2014). 1987; Still et al., 2019) but such calculations cannot answer questions about the non-local response. Flow buttressing numbers (Gudmundsson, 2013; Fürst et al., 2016) provide a summary view of the non-local effects but do not quantify the pinning point contribution to individual resistive stresses. We improve upon past work by conducting a modelling experiment in which the RIS and its tributary ice streams are simulated with and without the SCIR complex, using the Ice-sheet and Sea-level System 65 Model (ISSM) (Larour et al., 2012). Differences between the two models quantify the complete dynamical influence of the SCIR on the ice sheet–ice shelf system. Properties of the ice and subglacial bed, inferred during model initialisation, can also be examined using this approach. 2 Method 2.1 Ice sheet model 70 ISSM is an open-source, finite-element ice flow model that solves the conservation equations for mass and momentum in combination with appropriate boundary conditions and the constitutive relationship for ice (Larour et al., 2012). The Shallow Shelf (or shelfy-stream) Approximation (SSA) (Morland, 1987; MacAyeal, 1989) of the full-Stokes equations, appropriate for sliding over a very weak substrate such as water or water-saturated subglacial till, is used to simulate ice shelf and ice sheet flow. The fast flowing RIS ice streams draining the West Antarctic Ice Sheet are characterised by thawed bases and significant 75 sliding over soft subglacial till (MacAyeal et al., 1995; Joughin et al., 2004), justifying the SSA for the present study.
Load more

Recommended publications
  • Century-Scale Discharge Stagnation and Reactivation of the Ross Ice Streams, West Antarctica C
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, F03S27, doi:10.1029/2006JF000603, 2007 Click Here for Full Article Century-scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica C. Hulbe1 and M. Fahnestock2 Received 21 June 2006; revised 31 October 2006; accepted 10 January 2007; published 23 May 2007. [1] Flow features on the surface of the Ross Ice Shelf, West Antarctica, record two episodes of ice stream stagnation and reactivation within the last 1000 years. We document these events using maps of streaklines emerging from individual ice streams made using visible band imagery, together with numerical models of ice shelf flow. Forward model experiments demonstrate that only a limited set of discharge scenarios could have produced the current streakline configuration. According to our analysis, Whillans Ice Stream ceased rapid flow about 850 calendar years ago and restarted about 400 years later and MacAyeal Ice Stream either stopped or slowed significantly between 800 and 700 years ago, restarting about 150 years later. Until now, ice-stream scenarios emphasized runaway retreat or stagnation on millennial timescales. Here we identify a new scenario: century-scale stagnation and reactivation cycles, as well as lateral communication with adjacent ice streams through thickness changes on lightly grounded ice plains. This introduces uncertainty into predictions for future sea-level withdrawals by the West Antarctic Ice Sheet, which are based in part on recent slowing of Whillans Ice Stream and the stagnant condition of Kamb Ice Stream. Citation: Hulbe, C., and M. A. Fahnestock (2007), Century-scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica, J.
    [Show full text]
  • A Significant Acceleration of Ice Volume Discharge Preceded a Major Retreat of a West Antarctic Paleo–Ice Stream
    https://doi.org/10.1130/G46916.1 Manuscript received 26 August 2019 Revised manuscript received 23 November 2019 Manuscript accepted 26 November 2019 © 2019 Geological Society of America. For permission to copy, contact [email protected]. A signifcant acceleration of ice volume discharge preceded a major retreat of a West Antarctic paleo–ice stream Philip J. Bart1 and Slawek Tulaczyk2 1 Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803, USA 2 Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064, USA ABSTRACT SEDIMENT AND ICE DISCHARGE For the period between 14.7 and 11.5 cal. (calibrated) kyr B.P, the sediment fux of Bind- FROM THE PALEO–BINDSCHADLER schadler Ice Stream (BIS; West Antarctica) averaged 1.7 × 108 m3 a−1. This implies that BIS ICE STREAM velocity averaged 500 ± 120 m a−1. At a fner resolution, the data suggest two stages of ice Radiocarbon ages from benthic foramin- stream fow. During the frst 2400 ± 400 years of a grounding-zone stillstand, ice stream fow ifera (Bart et al., 2018) (Table 1) indicate that averaged 200 ± 90 m a−1. Following ice-shelf breakup at 12.3 ± 0.2 cal. kyr B.P., fow acceler- the paleo-BIS grounding line had retreated ated to 1350 ± 580 m a−1. The estimated ice volume discharge after breakup exceeds the bal- 70 km from its maximum (LGM) position by ance velocity by a factor of two and implies ice mass imbalance of −40 Gt a−1 just before the 14.7 ± 0.4 cal.
    [Show full text]
  • The Ministry for the Future / Kim Stanley Robinson
    This book is a work of fiction. Names, characters, places, and incidents are the product of the author’s imagination or are used fictitiously. Any resemblance to actual events, locales, or persons, living or dead, is coincidental. Copyright © 2020 Kim Stanley Robinson Cover design by Lauren Panepinto Cover images by Trevillion and Shutterstock Cover copyright © 2020 by Hachette Book Group, Inc. Hachette Book Group supports the right to free expression and the value of copyright. The purpose of copyright is to encourage writers and artists to produce the creative works that enrich our culture. The scanning, uploading, and distribution of this book without permission is a theft of the author’s intellectual property. If you would like permission to use material from the book (other than for review purposes), please contact [email protected]. Thank you for your support of the author’s rights. Orbit Hachette Book Group 1290 Avenue of the Americas New York, NY 10104 www.orbitbooks.net First Edition: October 2020 Simultaneously published in Great Britain by Orbit Orbit is an imprint of Hachette Book Group. The Orbit name and logo are trademarks of Little, Brown Book Group Limited. The publisher is not responsible for websites (or their content) that are not owned by the publisher. The Hachette Speakers Bureau provides a wide range of authors for speaking events. To find out more, go to www.hachettespeakersbureau.com or call (866) 376-6591. Library of Congress Cataloging-in-Publication Data Names: Robinson, Kim Stanley, author. Title: The ministry for the future / Kim Stanley Robinson. Description: First edition.
    [Show full text]
  • Studies of Seismic Sources in Antarctica Using an Extensive Deployment of Broadband Seismographs Amanda Colleen Lough Washington University in St
    Washington University in St. Louis Washington University Open Scholarship All Theses and Dissertations (ETDs) Summer 9-1-2014 Studies of Seismic Sources in Antarctica Using an Extensive Deployment of Broadband Seismographs Amanda Colleen Lough Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/etd Recommended Citation Lough, Amanda Colleen, "Studies of Seismic Sources in Antarctica Using an Extensive Deployment of Broadband Seismographs" (2014). All Theses and Dissertations (ETDs). 1319. https://openscholarship.wustl.edu/etd/1319 This Dissertation is brought to you for free and open access by Washington University Open Scholarship. It has been accepted for inclusion in All Theses and Dissertations (ETDs) by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. WASHINGTON UNIVERSITY IN ST. LOUIS Department of Earth and Planetary Sciences Dissertation Examination Committee: Douglas Wiens, Chair Jill Pasteris Philip Skemer Viatcheslav Solomatov Linda Warren Michael Wysession Studies of Seismic Sources in Antarctica Using an Extensive Deployment of Broadband Seismographs by Amanda Colleen Lough A dissertation presented to the Graduate School of Arts and Sciences of Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 2014 St. Louis, Missouri © 2014, Amanda Colleen Lough Table of Contents List of Figures .............................................................................................................................
    [Show full text]
  • Education Personal Research Interests Employment
    Douglas Reed MacAyeal Department of the Geophysical Sciences The University of Chicago 5734 S. Ellis Ave. HGS 424 Chicago, IL Phone: (773) 702-8027 (o) (773) 752-6078 (h) (773) 702-9505 (f) (224) 500-7775 (c) [email protected] [email protected] last updated: March, 2020 Education 1983 Ph.D. Princeton University, Princeton, NJ Geophysical Fluid Dynamics advisor: Kirk Bryan 1979 M.S. University of Maine, Orono, ME Physics/Glaciology advisor: Robert Thomas 1976 Sc.B. Brown University, Providence, RI Physics Magna cum laude, honors in physics Personal Birth Date: 8 December, 1954; Age: 65 Birth Place: Boston, MA, USA Marital Status: Married, Linda A. MacAyeal (Sparks) Children: Leigh C. (MacAyeal) Kasten (Brown U., Sc.B.; Cornell U., DVM), Hannah R. MacAyeal (U. Penn, B.S., U. Penn Veterinary Medicine, DVM), Evan C. MacAyeal (Carleton College, B.A., Columbia University, Financial Engineering, M.S.) Research Interests The physical processes that determine the evolution of ice and climate on Earth over the past, present and future. Employment Department of the Geophysical Sciences, University of Chicago 1983-Present Professor (Asst. until 1987, Assoc. until 1992 and Full until present) Prior to 1983: I was a graduate student at Princeton University and University of Maine. Awards and Honors • 2019 Seligman Crystal, International Glaciological Society (IGS) • 2013 Nye Lecture, American Geophysical Union (AGU), Fall Meeting • 2010 Goldthwait Award (Polar Medal) of the Byrd Polar Research Center, Ohio State University • 2005 Provost’s Teaching Award of the University of Chicago • 2002 Quantrell Teaching Award of the University of Chicago • 1997 Richardson Medal of the IGS • 1988 James Macelwane Medal of the AGU • 1988 Fellow of the AGU • Antarctic geographic names: MacAyeal Ice Stream, MacAyeal Peak Teaching Experience • GeoSci 242: Geophysical Fluid Dynamics, I.
    [Show full text]
  • Studies of Antarctic Ice Shelf Stability: Surface Melting, Basal Melting, and Ice Flow Dynamics
    Studies of Antarctic ice shelf stability: surface melting, basal melting, and ice flow dynamics by Karen E. Alley B.A., Colgate University, 2012 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree of Doctor of Philosophy Department of Geological Sciences 2017 This thesis entitled: Studies of Antarctic ice shelf stability: Surface melting, basal melting, and ice flow dynamics written by Karen E. Alley has been approved for the Department of Geological Sciences James White Ted Scambos Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above-mentioned discipline. ii Alley, Karen Elizabeth (Ph.D., Department of Geological Sciences) Studies of Antarctic ice shelf stability: Surface melting, basal melting, and ice flow dynamics Thesis directed by Senior Research Scientist T.A. Scambos and Professor J.W.C. White Abstract: Floating extensions of ice sheets, known as ice shelves, play a vital role in regulating the rate of ice flow into the Southern Ocean from the Antarctic Ice Sheet. Shear stresses imparted by contact with islands, embayment walls, and other obstructions transmit “backstress” to grounded ice. Ice shelf collapse reduces or eliminates this backstress, increasing mass flux to the ocean and therefore rates of sea level rise. This dissertation presents studies that address three main factors that regulate ice shelf stability: surface melt, basal melt, and ice flow dynamics. The first factor, surface melt, is assessed using active microwave backscatter.
    [Show full text]
  • Did Holocene Climate Changes Drive West Antarctic Grounding Line Retreat and Re-Advance?
    https://doi.org/10.5194/tc-2020-308 Preprint. Discussion started: 19 November 2020 c Author(s) 2020. CC BY 4.0 License. Did Holocene climate changes drive West Antarctic grounding line retreat and re-advance? Sarah U. Neuhaus1, Slawek M. Tulaczyk1, Nathan D. Stansell2, Jason J. Coenen2, Reed P. Scherer2, Jill 5 A. Mikucki3, Ross D. Powell2 1Earth and Planetary Sciences, University oF CaliFornia Santa Cruz, Santa Cruz, CA, 95064, USA 2Department oF Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL, 60115, USA 3Department oF Microbiology, University oF Tennessee Knoxville, Knoxville, TN, 37996, USA 10 Correspondence to: Sarah U. Neuhaus ([email protected]) Abstract. Knowledge oF past ice sheet conFigurations is useFul For informing projections of Future ice sheet dynamics and For calibrating ice sheet models. The topology oF grounding line retreat in the Ross Sea Sector oF Antarctica has been much debated, but it has generally been assumed that the modern ice sheet is as small as it has been for more than 100,000 years 15 (Conway et al., 1999; Lee et al., 2017; Lowry et al., 2019; McKay et al., 2016; Scherer et al., 1998). Recent findings suggest that the West Antarctic Ice Sheet (WAIS) grounding line retreated beyond its current location earlier in the Holocene and subsequently re-advanced to reach its modern position (Bradley et al., 2015; Kingslake et al., 2018). Here, we further constrain the post-LGM grounding line retreat and re-advance in the Ross Sea Sector using a two-phase model of radiocarbon input and decay in subglacial sediments From six sub-ice sampling locations.
    [Show full text]
  • Variability in the Mass Flux of the Ross Sea Ice Streams, Antarctica, Over the Last Millennium
    Portland State University PDXScholar Geology Faculty Publications and Presentations Geology 1-1-2012 Variability in the Mass Flux of the Ross Sea Ice Streams, Antarctica, over the last Millennium Ginny Catania University of Texas at Austin Christina L. Hulbe Portland State University Howard Conway University of Washington - Seattle Campus Ted A. Scambos University of Colorado at Boulder C. F. Raymond University of Washington - Seattle Campus Follow this and additional works at: https://pdxscholar.library.pdx.edu/geology_fac Part of the Geology Commons Let us know how access to this document benefits ou.y Citation Details Catania. G. A., C.L. Hulbe, H.B. Conway, T.A. Scambos, C.F. Raymond, 2012, Variability in the mass flux of the Ross Sea ice streams, Antarctica, over the last millennium. Journal of Glaciology, 58 (210), 741-752. This Article is brought to you for free and open access. It has been accepted for inclusion in Geology Faculty Publications and Presentations by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Journal of Glaciology, Vol. 58, No. 210, 2012 doi: 10.3189/2012JoG11J219 741 Variability in the mass flux of the Ross ice streams, West Antarctica, over the last millennium Ginny CATANIA,1,2 Christina HULBE,3 Howard CONWAY,4 T.A. SCAMBOS,5 C.F. RAYMOND4 1Institute for Geophysics, University of Texas, Austin, TX, USA E-mail: [email protected] 2Department of Geology, University of Texas, Austin, TX, USA 3Department of Geology, Portland State University, Portland, OR, USA 4Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA 5National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA ABSTRACT.
    [Show full text]
  • Information to Users
    Variations In Ice Flow And Glaciers Over Time And Space Item Type Thesis Authors Elsberg, Daniel Harry Download date 24/09/2021 03:40:40 Link to Item http://hdl.handle.net/11122/8657 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. VARIATIONS IN ICE FLOW AND GLACIERS OVER TIME AND SPACE A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Daniel Harry Elsberg, B.S.
    [Show full text]
  • Spatiotemporal Variations in the Surface Velocities of Antarctic Peninsula Glaciers
    Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | The Cryosphere Discuss., 8, 5875–5910, 2014 www.the-cryosphere-discuss.net/8/5875/2014/ doi:10.5194/tcd-8-5875-2014 TCD © Author(s) 2014. CC Attribution 3.0 License. 8, 5875–5910, 2014 This discussion paper is/has been under review for the journal The Cryosphere (TC). Spatiotemporal Please refer to the corresponding final paper in TC if available. variations in the surface velocities of Spatiotemporal variations in the surface Antarctic Peninsula glaciers velocities of Antarctic Peninsula glaciers J. Chen et al. J. Chen1,2, C. Q. Ke1,2, and Z. D. Shao1,2 1Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Title Page Nanjing University, Nanjing, 210023, China Abstract Introduction 2Key Laboratory for Satellite Mapping Technology and Applications of State Administration of Surveying, Mapping and Geoinformation of China, Nanjing University, Nanjing, 210023, China Conclusions References Received: 25 October 2014 – Accepted: 2 November 2014 – Published: 25 November 2014 Tables Figures Correspondence to: C. Q. Ke ([email protected]) J I Published by Copernicus Publications on behalf of the European Geosciences Union. J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 5875 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract TCD Velocity is an important parameter for the estimation of glacier mass balance, which directly signals the response of glaciers to climate change. Antarctic ice sheet move- 8, 5875–5910, 2014 ment and the associated spatiotemporal velocity variations are of great significance to 5 global sea level rise. In this study, we estimate Antarctic Peninsula glacier velocities Spatiotemporal using the co-registration of optically sensed images and correlation (hereafter referred variations in the to as COSI-Corr) based on moderate-resolution imaging spectroradiometer Level 1B surface velocities of data (hereafter referred to as MODIS L1B).
    [Show full text]
  • Fast-Flow Signature in the Stagnated Kamb Ice Stream, West Antarctica
    This is a repository copy of Fast-flow signature in the stagnated Kamb Ice Stream, West Antarctica. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/92154/ Version: Accepted Version Article: Ng, F. and Conway, H. (2004) Fast-flow signature in the stagnated Kamb Ice Stream, West Antarctica. Geology, 32 (6). 481 - 484. ISSN 0091-7613 https://doi.org/10.1130/G20317.1 Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Ng & Conway (G20317), p. 1 1 2 3 Fast-flow signature in the stagnated Kamb Ice 4 Stream, West Antarctica 5 Felix Ng 6 Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of 7 Technology, Cambridge, Massachusetts 02139, USA 8 Howard Conway 9 Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, 10 USA 11 12 ABSTRACT 13 Among the major ice streams that drain West Antarctica, Kamb Ice Stream 14 (formerly called Ice Stream C) is unique in that it stagnated ~150 yr ago, but its former 15 fast-flow conditions are virtually unknown.
    [Show full text]
  • Drainage Networks, Lakes and Water Fluxes Beneath the Antarctic Ice Sheet
    Annals of Glaciology 57(72) 2016 doi: 10.1017/aog.2016.15 96 © The Author(s) 2016. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons. org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Drainage networks, lakes and water fluxes beneath the Antarctic ice sheet Ian C. WILLIS,1 Ed L. POPE,1,2 Gwendolyn J.‐M.C. LEYSINGER VIELI,3,4 Neil S. ARNOLD,1 Sylvan LONG1,5 1Scott Polar Research Institute, Department of Geography, University of Cambridge, Lensfield Road, Cambridge CB2 1ER, UK E-mail: [email protected] 2National Oceanography Centre, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK 3Department of Geography, Durham University, Science Laboratories, South Road, Durham DH1 3LE, UK 4Department of Geography, University of Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland 5Leggette, Brashears & Graham, Inc., Groundwater and Environmental Engineering Services, 4 Research Drive, Shelton, Connecticut CT 06484, USA ABSTRACT. Antarctica Bedmap2 datasets are used to calculate subglacial hydraulic potential and the area, depth and volume of hydraulic potential sinks. There are over 32 000 contiguous sinks, which can be thought of as predicted lakes. Patterns of subglacial melt are modelled with a balanced ice flux flow model, and water fluxes are cumulated along predicted flow pathways to quantify steady- state fluxes from the main basin outlets and from known subglacial lakes. The total flux from the contin- − − ent is ∼21 km3 a 1. Byrd Glacier has the greatest basin flux of ∼2.7 km3 a 1.
    [Show full text]